Burner for coal dust firing



-May 23, 193 3. H. ZIKESCH 1 BURNER FOR COAL nusw FIRING Filed Feb. 9,1928 2 Sheets-Sheet 1 May 23, 1933. H, ZIKES H' 1,910,735

BURNER FOR COAIJ DUST FIRING Filed Feb. 9, 1928 2 Sheets-Sheet 2Jvzrerzfan Patented May 23, 1933 UNITED STATES PATENT OFFICE 4 HERBERTZIKESCH, OF UEBDINGEN-ON -'1HE-RHINE, GEEHANY, ASSIGNOR '10 BUTTNEB-A-G., 0F UERDINGEN-ON-THE-RHINE,

BURNER FOR COAL DUST FIRING Application filed February 9, 1928, SerialNo.

The invention pertains to a novel coal dust burner and to a process foroperating the same. According to the application, the case of the burneris given such a form and the supply conduits for the air and the-coaldust are arranged in such a way that a vortex of materials is producedin the case of the burner, in which there are air and' coal dust mixedwith each other. In this process the smallest particles are intended toform the core of the whirl and the coarser ones its outermost layers,while an equable combustion of the latter is provided for by envelopingthe whole of the coal dust air whirl with an outer air mantle.

The formation of the coal dust air whirl may be effected in differentways in accordance with the application, e. g. by conducting a mixtureof air and coal dust to the combustion chamber thru a central conduitdischarging into the said chamber, while inside the conduit an element,of helical form has been fitted, by which the coal dust air current ismade to turn or whirl. This whirling can be caused by .air currentstangentially introduced into the combustion chamber, the air currentsbeing preferably 'ticles contained in it.

conducted in such a way that they will closely pass along the inner wallof the combustion chamber'and thus completely envelope the coal dust airwhirl like a mantle.

It is particularly important to obtain marked layers in this coal dustwhirl. These will be produced, in accordance withthe invention, byshaping the combustion chamber in such a way as to enlarge it from thebottom gradually, or rather in form of steps. In this manner a gradualor a sudden expansion of the coal dust whirl in the transverse directionis attained. Thus the coarse particles are thrown outside, while thefine remain in the core of the whirl, from which -will result a markedarranging in layers of the coal dust air whirl in conformity with thesize of the coal dust par- For many purposes, particularly if theformation of a very short coal dust ilame shouldbe required, it hasproved advantageous to work such a burner with very high degrees of airspeed and 253,170, and in Germany February 14, 1927.

pressure far exceeding the speed and pressure hitherto in use. Insteadof the speed of about 12 metres at most, as is commonly used for thesupply'air and corresponds to a comparatively long flame of about 7 to 8metres, the applicant has advantageously applied, with the new burner,degrees of the speed of 20 metres rising to 50 metres and more a second.This is proportioned to an eduction speed at the nozzles of for instance20 to 45'metr es a second, as compared with 3' to 4 metres with theburner employed up to the present time. In a similar manner theapplicant has also raised the excess pressure for instance to 300-400millimeters and more, in opposition to 150200 millimeters of the usualoperation, while, for the secondary air current, he has appropriatelyapplied a pressure of at least 200'millimeters, against 35-40millimeters, for the air heater. For this process the blower producingthe pressure and supplying the secondary air current is preferablyarranged between the air heater and the burner. In this way a smallerdifference of pressure is obtalned between the smoke gas flues and theair passages than with the usual model, in which the blower was fittedin front of the air heater.

The working of this novel burner with a high speed and a high pressureresults in a considerable increase of the efiiciency of the burner withthe same dimension, as well as in a very short form of the flame, whichis but few metres long, that is, 2 to 3 metres. Therefore the operatormay render the heating power of this flame serviceable, in many cases,directly from the outlet of the case of the burner, without beingobligedto direct the flame round, that is, thru counter-blast currents.

Furthermore the high speed of the supply hill current he has evenapplied degrees of increased temperatures up to 450 C. and has found itto be specially advantageous to supply the secondary air current insteps. The best way is to. conduct the secondary air current treatedwith the highest preliminary heating to the mixture of coal dust and airleaving the burner.

In the subjoined drawings different forms of embodiment of the newburner have been represented.

Fig. 1 shows a burner with a gradually enlarging combustion chamber inits longitudinal section.

Fig. 2 is a cross section according to the line 2-'2 in Fig. 1.

Fig. 3 is a longitudinal sectional view of another 'formof burner.

Fig. 4 is a cross-section taken on line 4l.4 of Fig. 3.

Fig. 5 is a longitudinal sectional view of another form of burnershowing a stepped arrangement.

Fig. 6 is a cross sectional view taken on line 6-6 of Fig. 5. 1

Fig. 7 is a longitudinal sectional view of a further modified form ofthe invention showing particularly a variance ofcoal dust and airsupply.

ig. 8 is a cross sectional view taken on line 8-8 of Fig. 7.

Fig. 9 is a longitudinal sectional view of another form of theinvention, and

Figs. 10 and 11 are respectively a longitudinal section and across-section of a further form of the invention, Fig. 11. being takenon line 11-11 of Fig. 10. In particular, 1 shows the wall of thecombustion chamber made of fireproof material, the interior space of thesame being enlarged inthe shape of a bell towards the rear or dischargeopening. At the front end of the combustion chamber the supply of a coaldust air mixture is effected by means of a conduit 2. At the terminalpart of this conduit ahelical screw 3 is arranged, which serves forsetting the coal dust air current passing thru in a rotary and whirlingmotion.

The combustion chamber is surrounded with a case 4, the interior spaceof which is separated by a transverse wall 5 into two compartments 6 and7. llnto the latter rooms a secondary air current is introduced thru theconduit 8 and the branch conduits 9 and 10, which current is ledtangentially into the interior space of the combustion chamber thru theopenings 11, 12, 13, 141 in such a way that the air passes along theinterior face of the wall 1, cools the latter and, at the same time,cpm'pletely envelope the coal dust whirl formed inside. In this way anexcellent combustion even of the coarse outer particles of the whirl iswarranted.

Following the application, a supplemen- Fig. 1, such a burner is fittedto lie in the.

axis of the conduit 2. lln this case the helical screw 3 is given theform of a spiralshaped band and the auxiliary priming burner 15 ispassed through the interior hollow space at the center thereof.

With reference to Figs.- 3 and d the reference numbers are applied tothe corresponding parts of the burner as in Figs. 1 and 2 and areprimed. lln this instance the combustion chamber is formed with a squarecross section. lit enlarges in the shape of a funnel at 16, immediatelybehind the mouth of the supply conduit 2, then one part of it runs in astraight line, after which it enlarges once more like a funnel at 17.Consequently a double expansion of the coal dust air whirl thus takesplace in the enlarged funnel-like part and facilitates the Bil) exampleof the invention, two auxiliary,

priming burners are supplied. Preferably the latter should be arrangedin such a way that their flame is blowing obliquely or ten gentiallyinto the chambers. In this way the auxiliary priming flame, which isblowing in, is caused to contribute equally to the formation of the coaldust air whirl and to envelop the latter or, as it were, to be wrappedup in it, by which process the priming power of the flame is being fullyutilized. Eventually, in this instance as well as in the form ofembodiment corresponding to Fig. 1 or in other cases, the shape of theauxiliary priming flame may be measured big enough as to suficetemporarily for maintaining the operation if there should be anyinterruption and a diminution of the coal dust supply. 0n the otherhand, the auxiliary priming flame may also be put out of use after tion24 in Fig. 7 and the ste ped graduations 25 and 26 in Fig. 9. In t 1scase the coal dust air supply is not efi'ected from the front end, butfrom the side Walls of the combustion chamber and, as may be seen fromthe cross section in Fig. 8 schematically applying to both Figs. 7 and9, two coal dust supply-conduits 27 and 2,8 and two compressed airfeeders 29 and 30 in each case are alternately arranged round thecircumference of the combustion chamber. Air and coal dust will rushinto the interior of the compriming burner 35 is arranged inthe bottomof the combustion chamber. In conformity with Figure 9, also lateralauxiliary priming burners 36 and 37are provided, he-

I claim: y

1. A coal dust burner in which combustion is entirely efi'ected,including a burner body which is widened and enlarged in stepwiseformation from one end to the other, a longitudinally extending inletconduit connnunicating centrally with the small end of the body, meansin said inlet for forcibly introducing a whirling mixture of primary airand coal dust centrally of the burner body, the walls of the body beingprovided in each of the stepped portions with tangentially arranged airadmission openings through which secondary air is admitted to form aclosed layer of air adjacent the walls of the burner.

2. A burner as claimed in claim 1, wherein a secondary air containingcasing is provided about the stepped burner body and is provided withpartitions forming separate compartments for dividing the sald secondfary air casing into compartments corresponding to the stepped portionsof the body, and means for supplying secondary air'to each of saidcompartments.

In testimony whereof I aflix my signature.

HERBERT ZIKESCH.

side the auxiliary priming burner 35 fitted in the bottom of thecombustion chamber,

*which burners may enter obliquely or tangentially, so that their flameis wrapped up inside the coal dust air whirl.

After Figs. '10 and 11, the combustion chamber 38 is supplied with astepped graduation 39 and surrounded with a casing 40. Four coal dustsupply conduits 41, 42, 43, 44, which open into the longitudinal slits45, 46, 47, 48 introduced tangentially into the combustion chamber, arepassing thru the said casing. By means of the conduits 49, 50 the casing40 is provided with compressed air rushing into the differentcompartments of the combustion chamber thru the air slits. With thisform of embodiment too, a coal dust air whirl is obtained whichconsists, as it were, of bands and air bands we nd or wrapped on eachother. Moreover, a coal dust air mixture likewise set in a whirlingmotion and forming the core of the flame is conducted thru a conduit 51to the bottom of the combustion chamber, in which conduit lies a pieceofa screw face 52. An auxiliary burner 53 fitted in the axis of thesupply conduit 51 manages the priming of the coal dust flame.

The forms of embodiment described may be varied in manifold ways withinthe scope of the leading ideas of the invention. In

each case, the due formation in layers of the coal dust air whirl thruthe expansion obtained by means of a radual or ste dike enlargement ofthe com ustion cham er is of first consequence.

